1. Technical Field
The present invention relates to a green phosphor used in a plasma display panel (PDP) and a PDP including a phosphor layer formed of the green phosphor having improved luminance maintenance rate and color purity.
2. Related Art
Phosphors emit light when they are exposed to energy. Phosphors are used in light sources such as mercury fluorescent lamps or mercury free fluorescent lamps, electron emission devices, plasma display panels (PDPs), etc. In the future, phosphors will be used for a wider range of applications, as new multimedia devices are developed.
Plasma display panels (PDPs) are flat panel displays that display images using light emitted by ultraviolet rays that are created by discharge of a mixture of gases comprising neon and xenon injected into an area between a pair of glass substrates. At this point, visible light is created by each phosphor using resonance radiation light of Xe ion (147 nm vacuum ultra violet).
Phosphors for PDPs require good discharge characteristics, a high light emission luminance, good color coordinates and a short decay time. In PDPs, the composition of a material formed of a phosphor layer is different according to the colors of the phosphor layer, that is, red, green and blue, and surface discharge characteristics are different according to the type of material. When the surface of the material is positively discharged, there is a low probability of discharge failure. On the other hand, when the surface of the material is negatively discharged, there is a high probability of discharge failure. Such a probability of discharge failure is largely related to the driving method of PDPs. However, in order to increase discharge stability of PDPs and reduce the discharge failure rate thereof, red, green and blue phosphors having a positively discharged surface may be selected.
Zn2SiO4:Mn, which is a green phosphor that is commonly used in PDPs, has a negatively discharged surface. To address the problem described above, Korean Patent Publication No. 2001-0062387 discloses a green phosphor prepared by mixing Zn2SiO4:Mn and YBO3:Tb. However, the green phosphor disclosed in Korean Patent Publication No. 2001-0062387 has reduced color purity. Therefore, a phosphor prepared by mixing Zn2SiO4:Mn with (Ba,Sr,Mg)O.aAl2O3:Mn has been used to improve color purity of the phosphor. However, when the phosphor prepared using the above-described processes is used in a PDP, the lifetime of the PDP is significantly decreased.